Immunoadsorption is a medical procedure designed to remove specific harmful substances from a patient’s blood. It functions much like a highly specialized filter, targeting and extracting only particular “impurities,” which are typically disease-causing antibodies. This therapy involves circulating the patient’s blood outside the body, processing it, and then returning it. The goal is to alleviate symptoms or treat conditions where these specific antibodies contribute to illness or organ rejection processes.
The Immunoadsorption Process
The immunoadsorption process begins with the removal of blood from the patient, often through a venous catheter or two peripheral intravenous lines. This blood then enters an apheresis machine, which performs an initial separation of the plasma, the liquid component of blood, from the blood cells. Plasma separation is frequently achieved through centrifugation. The blood cells are temporarily held back and will be recombined with the purified plasma later.
The separated plasma then flows into an adsorber column. This column contains specific molecules, known as ligands, that are designed to bind only to the targeted harmful antibodies. These ligands act like highly selective magnets, capturing the undesirable antibodies as the plasma passes through the column. Different types of columns exist, each with a distinct active component, such as Protein A, ensuring selectivity for the specific antibodies of interest.
Once the plasma has flowed through the adsorber column, it is considered “cleaned” as the pathogenic antibodies have been removed. This purified plasma is then remixed with the patient’s own blood cells. The recombined blood is then returned to the patient’s body. Some systems utilize a dual-column setup, allowing one column to be actively processing plasma while the other is being regenerated, which facilitates continuous treatment.
Medical Applications
Immunoadsorption is employed in various medical contexts where the selective removal of antibodies can provide therapeutic benefits. It is considered for patients with conditions characterized by the presence of pathogenic antibodies or immune complexes, especially when conventional pharmacological treatments have not been sufficiently effective. Its targeted approach makes it suitable for specific immunological disorders.
In autoimmune diseases, the body mistakenly produces antibodies that attack its own tissues, leading to inflammation and damage. Immunoadsorption can be used to remove these autoantibodies. Specific examples include Myasthenia Gravis and Guillain-Barré syndrome, both neurological disorders where autoantibodies disrupt nerve or muscle function. Other conditions benefiting from this therapy include certain types of cardiomyopathy, rheumatoid arthritis, lupus, multiple sclerosis, and dermatological conditions like pemphigus and bullous pemphigoid.
Immunoadsorption also plays a role in transplant medicine, in preventing or treating antibody-mediated rejection of transplanted organs. Before a kidney or heart transplant, it can be used to desensitize highly sensitized recipients by removing pre-existing antibodies that would otherwise attack the new organ. This process makes transplantation possible for patients who might otherwise be ineligible due to their immune profile. Following transplantation, if antibody-mediated rejection occurs, immunoadsorption can remove the recipient’s antibodies that are targeting the transplanted organ, helping to preserve organ function and extend graft survival.
Comparing Immunoadsorption and Plasmapheresis
Immunoadsorption offers an advantage when compared to plasmapheresis, also known as plasma exchange. Plasmapheresis involves removing the entire plasma portion of the blood and replacing it with a substitute fluid, such as human albumin or fresh frozen plasma. This broader approach removes all plasma components indiscriminately, including beneficial elements like clotting factors and albumin, which may then need to be replenished. The removal of fibrinogen, a clotting factor, can be significant in plasmapheresis, potentially increasing bleeding risk.
In contrast, immunoadsorption is a selective therapy. After plasma is separated from blood cells, it passes through an adsorber column that binds only to the disease-causing antibodies. The rest of the patient’s own plasma, with its beneficial proteins and clotting factors, is then returned to the body along with the blood cells. This specificity means that important plasma constituents, such as albumin and coagulation factors, remain with the patient, reducing the need for fluid substitution and potentially lowering the risk of side effects associated with their removal.
The Patient Experience
Undergoing immunoadsorption involves practical and physical considerations. A single session typically lasts between 2 to 4 hours, though durations can range more widely depending on the volume of plasma treated and the specific adsorber used. The number of sessions in a course of treatment varies considerably based on the underlying condition and individual patient response, ranging from a few days to two years.
Vascular access is required for the procedure, which can be achieved through two peripheral intravenous lines, one for blood removal and one for return, or through a central venous catheter, especially for longer courses of treatment. Establishing this access is an initial step. While the procedure is generally well-tolerated, patients might experience some common, usually mild, side effects.
These potential side effects can include a temporary drop in blood pressure, known as hypotension, which may cause dizziness. Some patients may experience tingling sensations, particularly around the mouth or in the extremities, due to a reaction to the anticoagulant used to prevent blood clotting in the external circuit. Nausea, feeling cold, or general fatigue are also reported following treatment sessions. Medical staff closely monitor patients throughout the procedure to address any discomfort or adverse reactions promptly.